1. Field of the Invention
The present invention relates to light deflectors that change the traveling direction of light projected from behind, and to rear-projection screens.
2. Description of the Related Art
A conventional rear-projection screen is configured in such a way that the light exiting face of a Fresnel lens sheet provided with circular Fresnel lenses and the light incident face of a lenticular lens sheet straightly and vertically provided with cylindrical lenses (the vertical orientation along the screen) are faced closely each other (for example, Patent Document 1).
Another conventional rear-projection screen, which includes three lens sheets, that is, a lenticular lens sheet having cylindrical lenses that are straightly and vertically provided on both the light incident and light exiting face sides, a linear Fresnel lens sheet having Fresnel lenses that is straightly and horizontally provided (the horizontal orientation along a screen) on its light exiting face, and a circular Fresnel lens sheet having circular Fresnel lenses on its light exiting face, is configured in such a way that the lenticular lens sheet, the linear Fresnel lens sheet, and the circular Fresnel lens sheet are arranged in this order from a viewer side (for example, Patent Document 2).
Moreover, another conventional rear-projection screen, in order to reduce light losses, is composed of a set of, a prism piece in which a part of an incident light beam through one of its lens faces exits after having fully reflected on another lens faces, and a prism piece in which an incident light beam through its lens face exits after refracting; two kinds of these prism pieces are arranged so as to be alternately placed over the entire sheet (for example, Patent Document 3).
Moreover, another conventional rear-projection screen is, in order to reduce light losses in lenticular lenses, composed of a lens sheet having, a lens layer in which a plurality of unit lenses that can emits light from their light exit portions after a part of incident light being fully reflected by their fully reflecting portions are arranged one-dimensionally or two-dimensionally on the light exit portion, and a reflection reducing layer, in which light beams from its light incident portion are reflected and light beams from its light exit portion are reduced, provided on the fully reflecting portions for example, Patent Document 4).
Furthermore, in another conventional rear-projection screen, a light absorber is formed, which has a function for reducing light from outside and ghost light that travel obliquely in the screen (for example, Patent Document 5).
[Patent Document 1]
Japanese Laid-Open Patent Publication 196,422/2002 (on page 6, FIG. 2)
[Patent Document 2]
Japanese Laid-Open Patent Publication 64,189/1995 (on page 11, FIG. 2)
[Patent Document 3]
Japanese Laid-Open Patent Publication 52,601/1986 (on page 5, FIG. 4)
[Patent Document 4]
Japanese Laid-Open Patent Publication 311,211/2002 (on page 9, FIG. 3)
[Patent Document 5]
U.S. Pat. No. 5,254,388 (Sheet 1 of 2, FIG. 1)